Base support



FIG. 1 is a perspective side view of the base support of my new design;

FIG. 2 is an elevational view of the side opposite that shown in FIG. 1;

FIG. 3 is a perspective end view of the base support of my new design; and

FIG. 4 is an elevational view of the bottom of the base support of my new design. 

The ornamental design for a base support, as shown. 